CMV promoter: Human cytomegalovirus immediate early promoter. It drives transcription of viral RNA in packaging cells. This RNA is then packaged into live virus.
MMLV 5' LTR-ΔU3: A deleted version of the MMLV retrovirus 5' long terminal repeat. In wildtype MMLV retrovirus, 5' LTR and 3' LTR are essentially identical in sequence. They reside on two ends of the viral genome and point in the same direction. Upon viral integration, the 3' LTR sequence is copied onto the 5' LTR. The LTRs carry both promoter and polyadenylation function, such that the 5' LTR acts as a promoter to drive the transcription of the viral genome, while the 3' LTR acts as a polyadenylation signal to terminate the upstream transcript. On our vector, MMLV 5' LTR-ΔU3 is deleted for a region that is required for the LTR's promoter activity. This does not affect the production of viral RNA during packaging because the promoter function is supplemented by the CMV promoter engineered upstream of Δ5' LTR.
Ψ plus pack2: MMLV retrovirus packaging signal required for the packaging of viral RNA into virus.
Promoter: The promoter driving your gene of interest is placed here.
Kozak: Kozak consensus sequence. It is placed in front of the start codon of the ORF of interest because it is believed to facilitate translation initiation in eukaryotes.
ORF: The open reading frame of your gene of interest is placed here.
WPRE: Woodchuck hepatitis virus posttranscriptional regulatory element. It enhances viral RNA stability in packaging cells, leading to higher titer of packaged virus.
MMLV 3' LTR-ΔU3: A truncated version of the MMLV retrovirus 3' long terminal repeat. This leads to the self-inactivation of the promoter activity of the 5' LTR upon viral vector integration into the host genome (due to the fact that 3' LTR is copied onto 5' LTR during viral integration). The polyadenylation signal contained in MMLV 3' LTR-ΔU3 serves to terminates all upstream transcripts produced both during viral packaging and after viral integration into the host genome.
SV40 late pA: Simian virus 40 late polyadenylation signal. It further facilitates transcriptional termination after the 3' LTR during packaging. This elevates the level of functional viral RNA in packaging cells, thus improving viral titer.
pUC ori: pUC origin of replication. Plasmids carrying this origin exist in high copy numbers in E. coli.
Ampicillin: Ampicillin resistance gene. It allows the plasmid to be maintained by ampicillin selection in E. coli.